BETA uses the 26-meter dish with dual (east-west) feedhorns (and a
third low-gain terrestrial discone) to feed a 240 million channel
Fourier spectrometer (80 million channels of 0.5 Hz resolution and 40
MHz instantaneous bandwidth for each feed) whose outputs feed an array
of programmable "feature recognizers." These recognizers sift through
250 MByte/sec of spectral data, seeking distinctive spectral features
that transit from the east to the west horn without appearing in the
low-gain terrestrial antenna.

BETA's contemporary hardware consists of
HEMT low-noise frontends, an array of 63 quadrature mixer/digitizers
with GPS phase-locked local oscillators, and an array of 63
4-million-channel complex FFT boards feeding a flexible state-machine
based feature recognizer/correlator array resident in a set of Pentium
motherboards; the latter communicate with a UNIX workstation via
thin-wire Ethernet.

BETA searches the full "waterhole" of 1.4-1.7 GHz as 8 hops of 40
MHz, each hop taking 2 seconds (16 seconds for a full cycle through
the waterhole; thus each potential source is visited 8 times at each
frequency hop, in each sky beam). A good candidate (seen first in
east, then west, never terrestrial) triggers the antenna to leapfrog a
few beamwidths to the west, inviting the source to perform an
encore. If that ever happens, the antenna will break off its survey
and go into sidereal tracking mode, repeatedly moving on and off the
candidate source, archiving all integrated spectra.